240d dies @ idle - Page 5 - PeachParts Mercedes-Benz Forum

marktwain · #1 07-06-2009, 01:14 PM

hey all....I won't completely launch into my glorious introduction (complete with song and dance) and cryptic references to my former e-persona....but this isn't the first time that I've conversed with many of you silly dieselheads (and open forum goobers). Please humor me and my cantankerous 240d and kindly offer any suggestions.....

I've searched/tested/tried all that my feeble little mind can handle.....and I'm about ready to sell this blasted thing. As you can see in my signature, it's a 1981 240d - automatic - 152,000 miles. The car has always been in southeast PA and it's 85-90 degrees here right now.

Backstory....I'd say 90% of the fuel I've put in this beast has been regular petro diesel....but I think a bad batch of biodiesel set this off (bought from a questionable fuel pump)....and now I'm fighting some sort of fuel delivery problem. Right after I bought the car, I was plugging filters at an alarming rate on regular diesel but that symptom had mostly subsided (until now). So there you go....I posted/stated my car type and model and I'm not running veggie oil....so the unwritten forum rule is that you must help me now

1. About a month ago - after running essentially 6-7 gallons of B100 thru my car (added to half-tank of diesel)...it started shutting off at idle on my 30 mile commute home. I was always able to quickly restart and go - I thought it was just a plugged filter - and I made the drive home (I didn't have any spin-on filters in the car). I changed the primary and secondary filters at home - no change...it still would shut off at idle. The car begin to start with increasing difficulty.

2. Suspecting the biodiesel (tons of crud in both filters) I drained the contents back at the tank (5-6 gallons of bio)....and fuel was flowing freely, so I didn't think the tank strainer was clogged. I dumped 2-3 gallons of fresh petro diesel in the tank, primed it and it started....but still stalled @ idle. I thought I might just have some air bubbles in the lines due to draining it and for some reason....thought it would be a good idea to take it to a diesel station and fill it up. I drove it +/- 6 miles to the pump (kept my foot on the accelerator @ idle). At the diesel pump - it died and could NOT be restarted.

3. I noticed my primer pump was leaking (old knob style - replaced by me in 2007)....so I ordered a new bosch one and replaced it - thinking I was sucking in air. Replaced the 5 year old battery with a new bosch one (killed the old battery with all these hard starts)......and still.....shutting off at idle. I was able to get it back home via my now patented 'rev it like a crazy mofo in neutral with your left foot on the brake whilst ignoring all the curious onlookers' maneuver. Awesome.

Note: The starter is spinning fine and I'm always able to start the car by spraying WD40 down the intake and it will continue to run as long as my foot is on the accelerator. The car will not easily restart without the assistance of WD40 though and as SOON as I let the RPM's drop anywhere near what feels to be idle (no tach gauge in this 240d), it dies. Naturally I fiddled with the idle knob and settings out on the throttle linkage too.....it's not that.

4. Cracked each injector line and cranked.....and fuel is weeping out @ each injector. Pulled injectors and hard lines to see if clogged/obnoxiously dirty (not too bad) and soaked all 4 in carb cleaner and lightly brushed off and reinstalled. Cleaned banjo bolts @ main filter and IP and all the connecting lines - none were completely clogged (but definately with crud). Took off air filter housing and tried to start - nothing. Took off fuel filler cap to unlock potential vacuum, nothing. No noticeable fuel leaks or bad fuel lines. All lines are rubber or hazy amber.....so I can't see if bubbles are in the lines? I read the thread about the 603 engine shutting off at idle and the omniscient Brain C thinks air bubbles are getting thru...not sure if that's the case here. It's strange that it would coincide with a bad batch of bio and happen all at once though...but maybe not.

5. Blew out supply/return lines to tank with compressed air....thinking return line might be blocked. No help. Bypassed fuel tank and tried starting with clean fuel in 1 gal jug with supply/return lines...nothing.

So basically - I don't know where to turn? I know diesels needs fuel, air and heat/compression to work.....and fuel is getting to the injectors, it's 90 degrees here and poor compression doesn't happen all at once and my glowplugs are less than a year old (and new battery which is on a trickle charger) and the air filter is off? I

I'm also doing this troubleshooting myself....so the car isn't continually running on wd40 (meaning - I spray some down - go start and then keep it running by pressing the pedal) - so I *think* fuel is being delivered? I don't know how to rule out the IP or fuel pump but again - I'm getting fuel at the injectors. I also tested my fuel shutoff valve and it holds a vacuum....and it's also been replaced within the last 2 years too.

long story and waaaay too many words, I know - but hopefully I've explained myself thoroughly....and I'd be forever indebted for any of the forum's sage advice.

oh and I hate Swamp Yankee.